This project will investigate immunoregulation of the cell-mediated immune response of contact hypersensitivity to 1-fluoro-2,4-dinitrobenzene (DNFB). We will investigate the mechanisms of the induction of specific immunologic tolerance using hapten-modified lymphoid cells (DNP-LC) and soluble hapten-membrane preparations as tolerogens. Genetic restrictions of suppressor T cell induction will be determined as will the dual roles of suppressor cells and clone inhibition in maintenance of the tolerant state. Effort will also be made to identify the DNP-modified cell surface determinants responsible for tolerance induction and maintenance.